Adding a new custom post type using the editor causes 502 bad gateway error

I did some further research and testing, and found the issue to be related to nginx and not WordPress itself. The following Stack Overflow post included some configuration adjustments for the site’s config file that resolved the 502 bad gateway issues. My configuration file’s client_max_body_size was already set to 64M.

Here are the nginx settings I adjusted to resolve the issue:

fastcgi_temp_file_write_size 10m;
fastcgi_busy_buffers_size 512k;
fastcgi_buffer_size 512k;
fastcgi_buffers 16 512k;